One of the challenges in sending a medical device or portion thereof across a an internal body tissue wall is ensuring that the device is not advanced too far past the tissue wall, which can damage adjacent tissue structures. The use of minimally invasive surgical techniques, such as those employing catheters or other elongate surgical probes, complicate this challenge by taking certain aspects of a given medical procedure beyond the normal field of view of the surgeon. For example, conventional minimally invasive techniques for placing a trocar or needle across the atrial septum of a heart involves pushing a transseptal needle, such as those sold by Medtronic/AVE under the tradename “Brockenbrough™”, out of a introducer sheath and across the atrial septum, with guidance provided by a conventional imaging modality, such as fluoroscopy.
While conventional techniques, such as “over-the-guidewire” techniques, enable approximate positioning of a transseptal needle adjacent a targeted location upon the atrial septum, there is still no assurance that the needle is correctly positioned before advancement through the tissue wall. Further, it is difficult ascertaining whether the tip of the transseptal device been advanced across the tissue wall and into an adjacent cavity, and whether the cavity is, in fact, the targeted cavity.